1. Field of the Invention
The present invention relates to an improvement of a sealing structure of a rotary valve in an internal combustion engine. Particularly, the invention includes a recess provided either at the opening portion of a rotary valve proper or at the opening portion of a combustion chamber defined in a housing of a rotary valve proper, and a seal member slidably fitted in the recess and elastically pushed against the opposing part so as to effect sealing.
2. Description of Relevant Art
There has been known a rotary valve which opens and closes between the intake and exhaust passages and the combustion chamber of an internal combustion engine. The valve opens and closes by means of a rotator and replaces a valve of a mushroom-shape for use as intake and exhaust valves in an internal combustion engine.
In an internal combustion engine of such rotary valve type, various problems are caused due to high speed rotation of the valve. Such problems generally relate to the sealing between the intake and exhaust ports of the valve and the opening portion of the combustion chamber, which are opposite to each other in the respective intake and exhaust strokes.
An example of a rotary valve and its sealing structure is shown in FIG. 15. Above a piston 3 within a cylinder 2 of an internal combustion engine 1 is provided a rotor housing 4 as a cylinder head so as to form a combustion chamber therein. In the rotor housing 4 is formed a cylindrical rotor housing chamber 6 extended in a direction perpendicular to the axial direction of cylinder 2. A rotary valve proper 7 is provided in chamber 6. The rotary valve proper 7, which is of a cylindrical shape, has a hollow space 7a which communicates with an inlet passage 8a of an inlet manifold 8 so as to form a portion thereof. The rotary valve proper 7 also has an exhaust passage 7b which communicates with a passage 9a of an exhaust manifold 9 and is arranged so as to be separated and sectioned from the space 7a and extended therethrough. Ports 7c and 7d which open at the ends of passages 7a and 7b, are arranged so as to be angularly shifted from each other on the same plane in the radial direction of the rotary valve proper 7 and to selectively communicate with combustion chamber 5 therethrough. The rotary valve proper 7 is rotatively driven by a crankshaft arrangement via a sprocket 7e and a chain 7f and the like.
The sealing for the rotary valve is made by forming a circular recess 10 at the upper end of combustion chamber 5 and fitting a seal member 11 formed of ceramics, carbon or the like in circular recess 10. The sealing member 11, which is ring-shaped, is provided with a central opening having a diameter which corresponds to the inner diameter at the upper end of combustion chamber 5 and ports 7c, 7d. The sealing structure including seal member 11 is shown in FIGS. 13 and 14. A waved-spring washer 12 is interposed between the lower surface of seal member 11 and the bottom surface of recess 10 and a seal ring 13 is interposed in a ring-shaped groove 11b provided on the outer periphery of seal member 11, so as to seal between the outer periphery of seal member 11 and the inner periphery of recess 10.
In this arrangement, the seal member 11 is pushed by means of spring 12 towards the periphery of ports 7c and 7d of valve proper 7 to seal such portions. In the combustion stroke of the engine, the high pressure gas in the combustion chamber 5 exerts its pressure force upon seal member 11, and thereby seal member 11 is strongly pushed against the outer periphery of valve proper 7. At this instant, the gas passes through the gap of the spring 12, as indicated by the arrows in FIG. 14, and enters the space between the inner wall of recess 10 and the outer wall of seal member 11. Thus, seal ring 13 is pushed against the inner peripheral wall of recess 10 by means of the gas pressure, so as to prevent the leakage of gas. However, because seal ring 13, which effects the sealing between the inner wall of recess 10 and the outer peripheral wall of seal member 11, is formed in a disconnected circle as a result of mounting of seal ring 13 in ring-shaped groove 11b, a separation is necessarily formed at the juncture between the disconnected ends of seal ring 13. Thus, gas leaks from such separation and it thus becomes impossible to achieve effective sealing. In addition, the number of components increases due to the use of seal ring 13, and the structure for the sealing member becomes complex, for example, due to the fact that seal member 11 must be provided with the ring-shaped groove 11b.
The present invention effectively solves the above-described problems attendant the sealing structure of a conventional rotary valve.